Field of the Invention
This invention relates to a control circuit for a reciprocating electromagnetic apparatus, and in particular to an electromagnetic cutting apparatus.
The L. Hujik et al U.S. Pat. No. 4,095,536, issued June 20, 1978 discloses an electromagnetic cutting apparatus for cutting binding tape sewn to shoe upper components. The apparatus includes an electromagnetically operated plunger, photoelectric sensors for detecting the leading and trailing edges of the components and an electronic circuit for rapidly charging a coil surrounding a core on the plunger for driving the blade downwardly to cut the tape. Condensers in the electronic circuit are normally charged and, in response to signals from the photoelectric sensors, instantaneously discharge into the coil to actuate the plunger. After cutting the tape, the plunger is returned to the rest or starting position by a helical spring.
While the electronic circuit is effective for causing the blade and plunger to move down quickly against the tape, with thick tapes it is desirable to bring the knife and plunger down with a greater force. It will be apprecitated that the ability to move the plunger downwardly with a greater force is useful in any apparatus utilizing a plunger, e.g. for cutting or stamping.
The object of the present invention is to provide a control circuit for reciprocating electromagnetic apparatus which results in relatively rapid downward movement of a plunger, and consequently greater force of impact of the blade or other implement on the bottom end of the plunger.